In today’s world, it’s not uncommon for a business to partner with a marketing agency even if it has a full-time, in-house marketing team.

Whether it’s a specific project or ongoing partnership, many businesses realize they simply don’t have enough time and resources internally to accomplish everything that needs to be done from a marketing perspective.

However, marketing agencies come in all sorts of shapes and sizes; each has its own unique philosophy, approach, style and strengths. Some are better fits for your business than others — and vice versa.

While many businesses choose an agency because of an impressive creative portfolio or industry experience, the truth is that there’s a lot more that goes into a successful business-agency relationship. In many ways, it’s the intangible factors that make the biggest difference on both sides of the relationship.

So how can businesses and marketing agencies work together to form a relationship where everyone wins? Here are three key factors:

1) Chemistry across the entire team

When you hire a marketing agency, you’re ultimately hiring the people who work at that agency. As with all relationships, chemistry matters.

Part of determining a good fit comes down to selecting an agency that can operate as an extension of your team and roll up their sleeves to work with you, not just for you. That includes the leadership level and those responsible for executing the day-to-day project management tasks.

2) A common approach to business

Do you tend to take more risks or play it safe when it comes to growing your business? Are you looking for new and innovative ways to achieve your goals, or are you looking for someone to help execute tried-and-true principles. Answering these questions is essential for choosing the right agency partner.

3) Sweet spots that align with your greatest needs

Although most agencies consider themselves to be full-service, each has a “sweet spot” where it tends to excel. It might be web design, content creation, sales support or public relations.

Determining your greatest marketing need, even if you’re looking for a long-term partnership, is critical for finding the best possible fit.

As someone who’s worked in the agency business for more than a decade, I’ve seen my fair share of unhealthy client-agency relationships. No one starts working with an agency hoping it becomes a burden.

Taking the time to evaluate these qualitative factors (in addition to their portfolio or experience) will help you identify the right agency for your business and ensure everyone benefits from a successful partnership.